如何检查路径是否有效，而不使用try-catch？ [英] How to check if path is valid without using try-catch?

问题描述

我想检查一个文件夹是否存在，如果没有，请创建它。但我不知道提供的路径是否甚至有效。当路径无效时，会发生以下情况。

I want to check if a folder exists and if not then create it. But I don't know if the path supplied will even valid. When the path is not valid the following happens.

string path = "this is an invalid path";

if (!Directory.Exists(path))
    Directory.CreateDirectory(path); //Exception thrown here

如果提供无效的路径，它将抛出一个 DirectoryNotFoundException 异常。

If you supply an invalid path, it will throw a DirectoryNotFoundException exception.

如何阻止这种异常发生？我不想使用try-catch。我想检测到这个异常会发生在异常发生之前。

How can I stop this exception from occurring? I don't want to use a try-catch. I want to detect that this exception will occur even before the exception happens.

推荐答案

代码失败的解释是该路径无效。文件说：

The explanation for the failure of your code is that the path is invalid. The documentation says:

DirectoryNotFoundException

指定的路径无效（例如，它在
未映射的驱动器上）。

The specified path is invalid (for example, it is on an unmapped drive).

试图提前预测或不能创建一个目录是一个恶魔的工作。您需要考虑安全性，操作系统名称规则和限制，文件系统名称规则和限制以及驱动器是否映射。还有更多的关切。我不会考虑重新实现系统提供的免费。

Trying to predict in advance whether or not a directory can be created is a devil of a job. You'd need to account for security, OS name rules and limits, file system name rules and limits, and whether or not drives are mapped. And probably lots more concerns. I would not contemplate re-implementing what the system provides for free.

无论如何，您可以调用 Directory.Exists ，您仍然需要允许抛出异常。如果文件系统在调用 Directory.Exists 和后续调用 Directory.CreateDirectory 之间改变，那么一个异常将被提升。例如，如果另一个进程创建您要创建的目录。这是一个相当不太可能的事情，但这是完全可能的。

In any case, whilst you can call Directory.Exists, you do still need to allow for an exception being thrown. If the file system changes between the call to Directory.Exists and the subsequent call to Directory.CreateDirectory, then an exception will be raised. For example, if another process creates the directory that you are trying to create. Granted, this is a rather unlikely event, but it's perfectly possible.

总而言之，距离最远的一个选择是捕获异常。众所周知的说法是要求宽恕比要求许可更好。

In summary, the best option, by a distance, is to catch the exception. As the well known saying goes, it's better to ask for forgiveness than to ask for permission.

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